#distance
import math
x1,y1,x2,y2=map(float,input().split())
distance = math.sqrt((x2-x1)**2+(y2-y1)**2)
print(distance) import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 distance = math.sqrt((x2-x1)**2+(y2-y1)**2) distance math.sqrt((x2-x1)**2+(y2-y1)**2) math.sqrt math sqrt (x2-x1)**2+(y2-y1)**2 (x2-x1)**2 x2-x1 x2 x1 2 (y2-y1)**2 y2-y1 y2 y1 2 print(distance) print distance y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 y2=map(float,input().split()) map(float,input().split()) y2 x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1 distance = math.sqrt((x2-x1)**2+(y2-y1)**2) math.sqrt((x2-x1)**2+(y2-y1)**2) distance x2,y2=map(float,input().split()) map(float,input().split()) x2
#distance
import math
x1,y1,x2,y2=map(float,input().split())
distance = math.sqrt((x2-x1)**2+(y2-y1)**2)
print(distance)